Plastic electrical junction box

ABSTRACT

An electrical junction box is integrally molded of a synthetic organic plastic and includes rectangular side, rear and end walls defining a cavity for receipt of an electrical fixture and is open at its front. A pair of laterally spaced knock-out plugs are located on each end wall forwardly of its rear edge and each plug is delineated by front and side lines of weakness and a rear slot. A recess with parallel tool guiding side faces extends from each slot to the rear wall, the recess front edge being the slot rear edge and being downwardly rearwardly offset from the slot front edge. Integrally formed blocks extend along the inside corners between the rear wall and the end walls and have rear horizontal grooves with restricted throats oblique to the box rear face.

ilited States Patent [1 1 Brown PLASTIC ELECTRICAL JUNCTION BOX [75]Inventor: Leland A. Brown, Huntington Station, N.Y.

[73] Assignee: Electrical Fittings Corporation, East Farmsdale, NY.

[22] Filed: Nov. 17, I971 [2]] Appl. No.: 199,587

1 1 Nov. 6, 1973 Primary Examiner-Bernard A. Gilheany AssistantExaminerD. A. Tone Attorney-Howard C. Miskin [57] ABSTRACT An electricaljunction box is integrally molded ofa synthetic organic plastic andincludes rectangular side, rear and end walls defining a cavity forreceipt of an electrical fixture and is open at its front. A pairoflatcrally spaced knock-out plugs are located on each end wallforwardly of its rear edge and each plug is delineated by front and sidelines of weakness and a rear slot. A recess with parallel tool guidingside faces extends from each slot to the rear wall, the recess frontedge being the slot rear edge and being downwardly rearwardly offsetfrom the slot front edge. lntegrally formed blocks extend along theinside corners between the rear wall and the end walls and have rearhorizontal grooves with restricted throats oblique to the box rear face.

11 Claims, 7 Drawing Figures PAIENTEnnnv 6 :975 3,770,873

MMIIIIW W r-m INVENTOR. LELAND A. BROWN ATTORNEY.

PLASTIC ELECTRICAL JUNCTION BOX BACKGROUND OF THE INVENTION The presentinvention relates generally to improvements in electrical hardware andit relates more particularly to an improved electrical junction box.

The conventional electrical junction box, whether of the type employedas an outlet box or as a conductor junction box, is generally formed ofmetal, either by die casting or by stamping and forming from sheetmetal. The most widely used junction boxes are those which are formed ofsheet metal and die cast metal and these are provided with severalknock-out plugs in its walls, the knock-out plugs being delineated byscore lines to facilitate the separation of selected plugs to provideentrance openings at desired locations for the electrical conductors orcables. The conventional junction box possesses numerous drawbacks anddisadvantages. They are heavy and bulky devices which are expensive tofabricate and ship, difficult to employ and mount, especially on thinwall construction, of little versatility and otherwise leave much to bedesired.

SUMMARY OF THE INVENTION It is a principal object of the presentinvention to provide an improved electrical junction box.

Another object of the present invention is to provide an improvedintegrally molded electrical junction box.

Still another object of the present invention is to provide a moldedplastic electrical junction box having easily separable knock-out plugsfor providing selected conduit and cable access openings.

A further object of the present invention is to provide a junction boxof the above nature characterized by its ruggedness, low cost, ease ofmounting and high versatility and adaptability.

The above and other objects of the present invention will becomeapparent from the reading of the following description taken inconjunction with the accompanying drawing which illustrates a preferredembodiment thereof.

In a sense the present invention contemplates the provision of anelectrical junction box comprising an integrally molded box open at itsfront and including top and bottom end walls, side walls and a rearwall, defining a cavity for receipt of an electrical fixture, at leastone of the walls having lines of weakness formed therein delineating apart of the periphery of a knockout plug and a tool receiving slotdelineating the remainder of the knock-out plug periphery.

In the preferred form of the junction box which is formed of a syntheticorganic polymeric resin, a pair of laterally spaced knock-out plugs arelocated in the box top and bottom walls a short distance forwardly ofthe box rear wall or base, the plug delineating slots being positionedalong the rear edge of the plugs. Transverscly extending blocks areintegrally formed along the box top and bottom inside rear corner edges,and have forward edges which delineate the rear edges of the plugdelineating slots and which are rearwardly inwardly offset relative tothe slot front edges. Grooves are formed in the box top and bottom wallsextending from the plug slots to the box rear edge and have paralleltool guiding faces which extend to the ends of each slo A plug knocloouttool is provided which is of the width of the grooves and has a leadingend of a thickness equal to or slightly less than the vertical distancebetween the slot front and rear edges. Formed in the rear face of eachblock and extending horizontally for the full lengths thereof aretransverse slots having oblique restricted throats to slideably engagefasteners and facilitate the mounting of the box. Selected plugs may beknocked out merely by sliding the tool along a respective groove intoengagement with a corresponding slot and lowering the tool outer end tofracture the plug delineating lines of weakness and separate the plug.The edges of the fracture are smoothed.

The improved electrical junction box is rugged, inexpensive, highlyadaptable and easy to mount, and selected knock-out plugs may be easilyand rapidly removed.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front perspective view ofan electrical junction box embodying the present invention;

FIG. 2 is a sectional view taken along line 2 2 in FIG. 1;

FIG. 3 is a sectional view taken along line 3 3 in FIG. 2;

FIG. 4 is a fragmentary view similar to FIG. 2 illustrating theinsertion of a tool attendent to the separation of a knock-out plug;

FIG. 5 is a view similar to FIG. 4, the tool being shown in its leveredplug separating position;

FIG. 6 is a view similar to FIG. 4 with the plug removed and the toolbeing illustrated in a plug opening dcburring position; and

FIG. 7 is a perspective view, partially broken away, of the plugseparating tool.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,which illustrates a preferred embodiment of the present invention, thereference numeral 10 generally designates the improved electricaljunction box which may be of standard dimensions and molded in aconventional manner of any suitable synthetic organic polymeric resin,thermoplastic or thermoset, and advantageously of a nonflammable nature.The box 10 includes integrally formed substantially rectangularsubstantially similar top and bottom end walls 11, similar side walls 12and a rear wall, or base 13, the front borders of the end and side walls11 and 12 being reinforced by an integrally formed outerwardlyprojecting shallow peripheral band 14.

Disposed along the top and bottom inner corners of box 10 and extendingfor the full width of box 10 are transversely extending blocks 16 whichare integrally formed with side and rear walls 12 and 13 and havehorizontal top and bottom, or outer faces 17 which are inwardly offset ashort distance from the underfaces of the respective adjacent end wallsllll. Formed on the inner faces of end walls 11 and extending from thefront to the rear of end walls I 1 are medially positioned ribs 18 whichhave tapped axial coupling bores 19 in their forward ends. Alongitudinally extending medial groove 20 is formed in each end wall 11from the rear edge of band 14 to the rear edge of end wall 11.

A pair of laterally spaced knock-out plugs 21 are formed in the rearsection of each end wall ill on opposite sides of the groove 20. Thebottom face of each plug 21 is coplanar with the underface of acorresponding end wall and its top face is convex. The rear face 22 ofeach plug 21 is free and linear and vertical and extends transverselyand is positioned forward of and above the upper front edge of therespective block 17. The side and forward edges of each plug 21 aredefined by' a U-shaped line of weakness 24 which is a line of reducedthickness in end wall 11, the side legs of the line of weakness 24extending forwardly from the ends of rear face 22 and being joined by anarcuate front section. The top face of the plug 21 slopes downwardlyfrom its longitudinal medial axis to the line of weakness 24.

A longitudinal recess 26 located in end wall 11 extends rearwardly fromeach plug rear face 22 to the rear edge of end wall 11 and has parallelside faces 27, which are colinear with the side legs of the line ofweakness 24. The base of each recess 26 is defined by a correspondingblock top face 17. The front edge 23 of each block outer face 17 isrearwardly inwardly offset from and parallel to the inner edges of plugrear faces 22 and defines therewith transverse slots 28.

A longitudinal horizontal groove 29 is formed in the rear face of andextends for the full length of each block 16, the inner face or base 30of the groove being oblique to the plane of the rear face of rear wall13, as shown in FIG. 3. A longitudinal rib 32 is formed on a side faceof each groove 29 parallel to and spaced rearwardly of the base 30thereof and extends between points short of the ends of the respectivegroove 29 to define a restricted throat 33 to the inner section ofgroove 29. The grooves 29 facilitate the mounting of the box 10, thegrooves 29 being slid at the shallow end thereof over the head of'asuitably secured fastener with the enlarged head of the fastener locatedbetween groove base 30 and ridge 32, and sliding the box laterally todraw the rear wall 13 into tight engagement with the fastener supportingwall as urged by the fastener head bearing on the inside face of ridge32. To also facilitate the mounting of the box 10, a pair of verticallyspaced medially located annular ridges 34 are formed on the inner faceof rear wall 13 and a circular recess 36 coaxial with each ridge 34 isformed in the rear wall front face to provide a thin easily piercablesection in rear wall 13 coaxial with each ridge 34.

The tool 37 for removing selected plugs 21 is formed of a hard material,for example a tool steel, and includes an elongated rectangular shank 38of a width equal to or slightly less than that of recess 26. The distalend section 39 of tool 37 is integrally formed with shank 38 and is oflesser thickness and delineated therefrom by a transverse shoulder 40.The thickness of the distal section 39 is approximately equal to thevertical spacing between slot edges 22 and 23 and the end periphery ofdistal section 39 is arcuate and the length of the distal section 39 isless than that of plug 21. The peripheral face 41 of distal section 39is bevelled to provide a cutting edge 42 along the plane of the offsetface of distal section 39. The underface of distal section 39 and shank38 are coplanar.

In removing a knocloout plug 21, tool 37 is inserted through the rearend of a recess 26 and slid along the base 17 thereof as guided by sidefaces 27 to slide the tool distal section'39 through slot 28 until theshoulder 40 abuts the plug rear face 22 and the top face of tool distalsection 39 underlies the underface of plug 21, as shown in FIG. 4. Theouter end of tool 37 is then depressed to swing it counter-clockwiseabout the rear upper edge of block 16, as shown in FIG. 5, to sever orrupture end wall 11 along line of weakness 24 and subopening, as shownin FIG. 6, and rotating and otherwise manipulating the tool 27 to deburand smooth the opening by means of the cutting edge 41.

While groove 29 is illustratively shown at an angle to the plane of therear face of rear wall 13, it could be parallel also.

While there has been described and illustrated a preferred embodiment ofthe present invention, it is apparent that numerous alterations,omissions and additions may be made without departing from the spiritthereof.

What I claim is:

1. An electrical junction box comprising an integrally molded box openat its front and including top and bottom end walls, side walls and arear wall, defining a cavity for the receipt of an electrical fixture,at least one of said walls having lines of weakness formed thereindelineating a part of the periphery of a knock-out plug and a toolreceiving slot providing communication-between the interior and exteriorof said box and delineating the remainder of said knock-out plugperiphery and being approximately equal in length to the maximum widthof said plug, the surface of the knock-out plug which faces the interiorof box being substantially flat and being located outwardly relative tothe portion of the box on the opposite side of the slot, whereby topermit the receipt and positioning of a plug knock-out tool with anouter edge approximately the shape of said lines of weakness.

2. The electrical junction box of claim 1 wherein said knock-out plug islocated in the rear portion of one of said end walls, said slot beingpositioned along the rear of said knock-out plug.

3. The electrical junction box of claim 2 wherein said slot is forwardof and parallel to the rear edge of said respective end wall.

4. The electrical junction box of claim 3 including a recess formed insaid respective end wall extending from said slot to the rear edge ofsaid end wall, and having a shoulder defining base below said end walland having a leading edge delineating the rear edge of said slot andbeing inwardly rearwardly offset relative to the forward edge of saidslot.

5. The electrical junction box of claim 4 including a laterally spacedpair of said knock-out plugs and recesses positioned on said end wall.

6. The electrical junction box of claim 4 including a laterally spacedpair of said knock-out plugs and recesses positioned on each of said endwalls.

7. The electrical junction box of claim 4 wherein said recess haslongitudinally extending parallel side faces defining a tool guide.

8. The electrical junction box of claim 4 including a block integrallyformed with said box and extending along the inner faces of said end andrear walls at the corner thereof, the top face of said block definingsaid base of said recess. v

9. An electrical junction box comprising an integrally molded box openat its front end and including top and bottom end walls, side walls anda rear wall, defining a cavity for the receipt of an electrical fixture,at least i one of said end walls having lines of weakness formed thereindelineating a part of the periphery of a knockout plug and toolreceiving slot delineating the remainder of said knock-out plugperiphery and positioned along the rear of said knock-out'plug andforward of and parallel to the rear edge of said respective end wall,said end wall having a recess formed therein extending from said slot tothe rear edge of said end wall, said recess having a shoulder definingbase below said end wall and having a leading edge delineating the rearedge of said slot and being inwardly rearwardly offset relative to theforward edge of said slot, a block integrally formed with said box andextending along the inner faces of said end and rear walls at the cornerthereof, the top face of said block defining said base of said recessand said block having a groove formed in and extending the length of therear face thereof and having a restricted throat rearwardly of its innerend.

10. The electrical junction box of claim 9 wherein said groove isoblique to the rear face of said rear wall.

11. An electrical junction box comprising an integrally molded box openat its front end and including top and bottom end walls, side walls anda rear wall, defining a cavity for the receipt of an electrical fixture,at least one of said end walls having lines of weakness formed thereindelineating a part of the periphery of a knock-out plug, said end wallhaving a recess formed therein, a block integrally formed with said boxand extending along the inner faces of said end and rear walls at thecomer thereof, the top face of said block defining said base of saidrecess and said block having a groove formed in and extending the lengthof the rear face thereof and having a restricted throat rearwardly ofits inner end.

1. An electrical junction box comprising an integrally molded box openat its front and including top and bottom end walls, side walls and arear wall, defining a cavity for the receipt of an electrical fixture,at least one of said walls having lines of weakness formed thereindelineating a part of the periphery of a knock-out plug and a toolreceiving slot providing communication between the interior and exteriorof said box and delineating the remainder of said knock-out plugperiphery and being approximately equal in length to the maximum widthof said plug, the surface of the knock-out plug which faces the interiorof box being substantially flat and being located outwardly relative tothe portion of the box on the opposite side of the slot, whereby topermit the receipt and positioning of a plug knock-out tool with anouter edge approximately the shape of said lines of weakness.
 2. Theelectrical junction box of claim 1 wherein said knock-out plug islocated in the rear portion of one of said end walls, said slot beingpositioned along the rear of said knock-out plug.
 3. The electricaljunction box of claim 2 wherein said slot is forward of and parallel tothe rear edge of said respective end wall.
 4. The electrical junctionbox of claim 3 including a recess formed in said respective end wallextending from said slot to the rear edge of said end wall, and having ashoulder defining base below said end wall and having a leading edgedelineating the rear edge of said slot and being inwardly rearwardlyoffset relative to the forward edge of said slot.
 5. The electricaljunction box of claim 4 including a laterally spaced pair of saidknock-out plugs and recesses positioned on said end wall.
 6. Theelectrical junction box of claim 4 including a laterally spaced pair ofsaid knock-out plugs and recesses positioned on each of said end walls.7. The electrical junction box of claim 4 wherein said recess haslongitudinally extending parallel side faces defining a tool guide. 8.The electrical junction box of claim 4 including a block integrallyformed with said box and extending along the inner faces of said end andrear walls at the corner thereof, the top face of said block definingsaid base of said recess.
 9. An electrical junction box comprising anintegrally molded box open at its front end and including top and bottomend walls, side walls and a rear wall, defining a cavity for the receiptof an electrical fixture, at least one of said end walls having lines ofweakness formed therein delineating a part of the periphery of aknock-out plug and tool receiving slot delineating the remainder of saidknock-out plug periphery and positioned along the rear of said knock-outplug and forward of and parallel to the rear edge of said respective endwall, said end wall having a recess formed therein extending from saidslot to the rear edge of said end wall, said recess having a shoulderdefining base below said end wall and having a leading edge delineatingthe rear edge of said slot and being inwardly rearwardly offset relativeto the forward edge of said slot, a block integrally formed with saidbox and extending along the inner faces of said end and rear walls atthe corner thereof, the top face of said block defining said base ofsaid recess and said block having a groove formed in and extending thelength of the rear face thereof and having a restricted throatrearwardly of its inner end.
 10. The electrical junction box of claim 9wherein said groove is oblique to the rear face of said rear wall. 11.An electrical junction box comprising an integrally molded box open atits front end and including top and bottom end walls, side walls and arear wall, defining a cavity for the receipt of an electrical fixture,at least one of said end walls having lines of weakness formed thereindelineating a part of the periphery of a knock-out plug, said end wallhaving a recess formed therein, a block integrally formed with said boxand extending along the inner faces of said end and rear walls at thecorner thereof, the top face of said block defining said base of saidrecess and said block having a groove formed in and extending the lengthof the rear face thereof and having a restricted throat rearwardly ofits inner end.